RHS Super Dirt Late Model LS7 Engine Build - Part 2

Check out Part 1 and Part 3 of this series on building the next generation race engine!

There is a syndrome unique to magazine staffers—particularly the dirty-hands car and magazine books—which in terms of embarrassment is the equivalent of walking around all day with your fly open. It goes by various names, but the most common scientific term is “Stalled Build Project.” The symptoms are easy to identify—a magazine begins a new project with great fanfare, but then fails to show up in subsequent issues. In mild cases of SBP, the project will sheepishly show up again a few issues down the row, but some cases of SBP can be fatal with the unfortunate project never to be seen again. Unfortunately, we’ve tested positive for the affliction.

2/28After a little bit of a break while we rounded up parts, veteran engine builder Bob Cronin, owner of CRD Engine Development, mocks up our LS7 engine in preparation for the build.

Since taking over the helm, editor Fisher has encouraged everyone at Circle Track not to simply report the status quo, but to push the boundaries of what’s possible with stock car racing technology. It has been a great mandate that has allowed the magazine to build an environmentally friendly race car (E85 burning Project GREEN) among other fun and really cool projects. Our latest has been in planning for months that hopefully will make a real impact on the racing landscape and not simply be just another series of magazine articles.

The idea is to take a look at Chevrolet’s LS engine technology to see how well it will work as a replacement for the venerable small-block. And since we never take the easy way out, we started with one of the toughest challenges we could think of—Dirt Late Model racing. And while the LS is still in production (unlike the small-block) and OEM components are easily available, we decided to test the aftermarket to see how difficult it would be to source race-quality components.

So it was with enthusiasm that we kicked off the LS7 build project featuring RHS’s excellent aluminum block and CNC-cut cylinder heads all the way back in the June ’13 issue of Circle Track. We took a look at the major components we planned to use, how the LS architecture is different from the classic small-block we’re all already familiar with, and introduced engine builder Bob Cronin who is leading the build project.

And then…nothing.

Stalled build project. It happened when we jumped the gun with the build, but still lacked a few critical components. Part of the problem is the LS7 hasn’t been around as long as the LS1 and other variations, so there were a few holes when we looked for components that could hold up to the rigors of oval track racing in the big leagues. Jesel saved our hides when they stepped up and designed a new set of shaft mount roller rockers for the LS7 heads. We also want to start out with a carbureted setup for the engine (but we’re reserving the right to test fuel injection in the future) and discovered that the options for a carb’ed intake are limited. It left us making a few unexpected phone calls while deadlines passed unmet.

Thankfully, our case of Stalled Build Project was mild and we’re back. We’re still trying to sketch out the best option for an oil pan that will work with a rear-mount oil pump and won’t interfere with a Dirt Late Model chassis’ suspension pickup points, but we’ve thrown salt over our shoulder and crossed our fingers, so we’re confident we’ll have the solution when the time comes. That doesn’t mean we won’t miss another deadline, but we have the best intentions, and mother says that counts for a lot.

This time around Bob Cronin, who is one of the leading LS-based race engine builders for sports car racing, mocks up our DLM LS7. Regardless of what engine you are building, properly mocking up the engine before the build can help avoid fitment issues and other pitfalls. Follow along to see how we install this build and get back on the LS7 horse.

Intake Intrigue
Even though we’ve enlisted the help of some of the best LS experts available, this buildup series is more of an experiment than a how-to on building the perfect LS engine. That’s because an LS7 has never been built to race in a Super Dirt Late Model car before, so we’re learning as we go.

And the induction system is definitely going to be a learning area. The problem is there just isn’t a wide variety of cast aluminum intakes for mounting a carb to the LS7. Originally, we had hoped to use Edelbrock’s excellent Victor intake, but it turns out the Victor unit is for the LS1 and won’t fit our LS7 heads. So we turned to Pace Performance and they set us up with a cast single-plane intake from Chevrolet Performance—which, at the time, was the only intake we could find that works. There may be other carbureted options available for the LS7 by the time you read this.

The Chevrolet Performance intake we are using—PN 25534394—is a nice piece but it is designed to work best on a hot rod and not a full-out race car so the ideal rpm range may be a bit lower than what we need. We took the intake to induction specialist MBE Cylinder Heads & Manifolds to see what could be done. MBE produces winning induction systems for everything from Dirt Late Models to Sprint Cars and Top Fuel drag racers, and when owner Matt Bieneman offered to cut up the intake, port it, and weld it back up as a completely new creation, we knew he could do it, but declined since that’s not the goal of the project. But we did take them up on their offer for a little light porting work to maximize this intake’s capabilities

MBE owner Matt Bieneman builds winning intakes int he top levels of both circle track racing and rag racing, and he immediately saw where the LS7 intake we brought him might be lacking on the track. For comparison, he pulled out one of the MBE's own intakes for a 13-degree Chevrolet engine, which is the current state of the art in Super Dirt late Models. Notice how much shorter our intake is on the left. The runners also don't have line-of-sight like the racing intake on the left. Matt says we can make up so me of the difference with carb spacers, but that's a compromise and not a perfect solution.

24/28MBE owner Matt Bieneman builds winning intakes in the top levels of both circle track racing and drag racing, and he immediately saw where the LS7 intake we brought him might be lacking on the track. For comparison, he pulled out one of MBE’s own intakes for a 13-degree Chevrolet engine, which is the current state of the art in Super Dirt Late Models. Notice how much shorter our intake is on the left. The runners also don’t have line-of-sight like the racing intake on the left. Matt says we can make up some of the difference with carb spacers, but that’s a compromise and not a perfect solution.

28/28MBE’s intake specialist Norman Jacob mocks up the intake using our RHS heads and a mockup LS block to see how well the intake’s ports match up.